I have the problem that a server is rejecting emails from my mail server if they are replies to previous mails. If a new mail is sent it can be delivered.
Either I receive this error message
host mail.example.com[x.x.x.x] said: 554 5.7.1 Command rejected (in reply to end of DATA command)
or I do not get any message but only an empty message is delivered to the receiver.
I've tested my server with http://www.mxtoolbox.com/ for blacklist entries or SMTP errors but everythink looks fine. The receiving server also has no SMTP errors, except it doesn't accept SSL/TLS connections.
The mails are sent/replied with Outlook 12. My mail server runs postfix and dovecot.